Margin can refer to borrowing to buy securities or collateral supporting a short option obligation. These are different uses of the same word.
Requirements depend on the position
Option requirements depend on the underlying, exercise and settlement terms, offsets, account approval and applicable strategy-based or portfolio-margin rules. Brokers may set higher house requirements and change them. A generic online estimate is not an exact account requirement.
Buying options and holding spreads
Long options are generally paid for in full, with specific exceptions for eligible long-dated options. Do not assume that every option is marginable or that a fixed percentage applies to every account. Ask the broker how an assignment or an expiring protective leg would change the requirement.
Collateral is not a loss limit
A margin deposit does not cap loss. Uncovered calls can have unlimited loss potential as the stock rises. Short puts on a nonnegative stock have finite but potentially substantial losses if the stock falls to zero. A cash-secured put reserves funds for assignment; it still exposes the investor to the stock's downside.
Margin borrowing incurs interest and can lead to liquidation without advance notice under the account terms. Use the payoff calculators for stated expiration scenarios, not as a broker margin calculator.
Content reviewed:
Primary references: FINRA margin rules; Cboe strategy-based margin; OCC risk disclosure. Editorial standards.